Manufacture of rayon



April 13, 1933. G R LOCKHART 1,904,377

MANUFACTURE OF RAYON Filed March 24, 1930 3 Sheets-Sheet l o o o o o o o o o o o :0 o o o 0 0/ 0 0 o o o ooo o 000000000 coo o z zooooooooo 00000060000 00000000000 April 9 R. LOCKHART 1904'377 MANUFACTURE OF RAYON Filed March 24, 1930 3 Sheets-Sheet 2 Fyz Wbiizes A ril 18,- 1933.. a R LOCKHART 1,904,377

' MANUFACTURE OF RAYON Filed March 24, 1930 3 Sheets-Sheet 3 1 Q f *4% i $7M... m

Patented Apr. 18, 1933 UNITED STATES PATENT OFFICE GEORGE E. LOCKHZAIRT, OF PROVIDENCE, RHODE ISLAND, ASSIGrIN'ClIR. TO MANVILLE JENGKES COMPANY, OF PAWT'UGKET, RHODE ISLAND, A CORPORATION OF RHODE ISLAND MANUFACTURE OF RAYON Application filed March 24, 1930. Serial No. 438,370.

The present invention relates to rayon (artificial silk) and processes of making rayon and is intended primarily as an improvement in the production of rayon from viscose by the pot spinning process, although in certain aspects the invention is applicable to the production of rayon from other substances and by other spinning processes.

In the pot spinning method of manufacturing rayon at present in use, a cellulose solution such as viscose, is precipitated in the form of slender fibrous filaments by forcing the solution through a spinneret into a precipitating or setting bath. The filaments are then gathered together to form a thread and the thread is guided to a centrifuge pot by which it is twisted and formed into a socalled cake.

Before the thread thus formed and deposited in cake form at this stage in the process is ready'for commercial use, it is necessary to subject the thread to a number of processlng operations to remove the large amounts of impurities carried over from the spinnlng bath and otherwise put the thread in a commercial form. These operations may include desulphurizing, washing, bleaching, sizing, dyeing,'etc.

Previously, in order to secure a thorough and even penetration of the threads by the liquids utilized in these steps to produce a thread of uniform quality with high luster and tensile strength, and at the same time to leave the thread mass in a form which will permit the finished thread to be readily wound onto spools or quils without snarling or breaking, it has been found necessary first to wind the thread from the cake into skeins which are then processed as above pointed out. These subsequent operations on the thread while in 'skein form contribute a large part of the expense in the manufacture of rayon, not only because of the time and labor required, but also because of the difficulty sarily harsh treatment to which the skeins are subjected.

In carrying out the present invention, it

is proposed to perform the various processing operations. required to produce thev thread in its finished state while'the thread The invention, therefore, has for its principal object to provide a method of handling the cakes in such a manner as to permit the various processing operations to be performed on the original cake so that they will take efl'ect in a thorough and uniform 'manner throughout the thread mass and at the same time, will leave the cake in such a form that the finished thread may be readily wound therefrom onto quills or spools without any snarling or breaking of the thread.

The application of the present method in carrying out the invention will be clear to one skilled in the art from the following description taken in connection with the accompanying drawings in which Fig. 1 is a perspective View of a cake as it is taken from the pot; Fig. 2 is a view similar to Fig. 1 in tions; Fig. 8 is a view in side elevation of a drying chamber and a truck on which the cakes are supported during the drying operation; Fig. 9 is an end View of the truck shown in Fig. 8; and Fig. 10 is a somewhat diagrammatic view partly in section of a winding machine on which the cakes are placed for winding from the cake onto bobbins or spindles.

In carrying out the method of the present invention, the cakes are flattened out to secure a substantially solid thread mass and are then closely packed in a container through which the various liquids utilized inthe processing operation are passed under a Suitable pressure. The cakes are finally opened out and dried in substantially their original cylindrical shape so that the thread may be drawnreadily from the cake for winding onto quills or spools.

The difficulties inherent in this method of handling the rayon thread in the cake form during the operations in which it is brought to its finished state arise principally from the change in the nature and composition of the thread mass during this period. As the impurities carried over into the cake from the coagulating bath are removed, the cake is reduced to approximately one-fourth of its original weight and the threads which were built up into a tightly compacted mass in I the formation of the original cake are left in a loose coil of roughly cylindrical shape so that it becomes essential to use the greatest care to prevent disarrangement or snarling of the threadswith the consequent difliculty in winding from the cake onto spools, quills, orbobbins. In order to maintain thethreads in their original positions in the cakes during the processing operations and more particularly to enable the cake to be opened out into its cylindrical shape after completion of the processing operation above referred to, without disturbing the thread structure, one feature of the method herein disclosed contemplates the provision of porous wrappings or cloths which are passed through the aperture formed in the middle of the cake to support and separate the inner walls of the cake when it is flattened out so that it ma readily be opened out again without disturbing the relationship of the loose fibers. The

ends of these Wrappings are preferably folded over the outside of the cake and another Wrapping is then placed around the outside of the cake in its flattened shape to form an additional protection against injury to the thlrleads in the subsequent handling of the ca e.

After the cakes have been flattened and wrapped as above described, they are closely packed in a container provided for the purpose and are then subjected to the successive desulphurizing, bleaching, washing and other operations required to produce the finished thread. The outer wrapping is then removed, and the cakes are opened out and ning process in a centrifuge pot or vessel and then aged for a number 0 hours to allow the filaments to be completely hardened, are now taken out and prepared for the processing operations which are necessary to put the thread in its final or commercial form. First, two loose mesh cloths-0r wrappings 10 are inserted through the center of the cake 12 as best indicated in Fig. 2, and folded over so that ends of each wrapper are brought together on the outside of the cake. The cake is now flattened out by hand to bring the two wrappings together on opposite sides of the cake, as shown in Fig. 3, and another wrapping 14 (see Fig. 4), is placed around the outside of the cake to hold it together and to prevent injury to the threads during the subsequent processing operations.

The kier or bleach tank in which the cakes are now packed for the several processing operations such as desulphurizing, washing and bleaching, comprises a strongly built oblong tank generally indicated at 16 in Fig. 5, provided with a cover 18 which is adapted to be clamped tightly in position by means of clamps 20 which engage corresponding flanged portions of the tank and the cover. A supply pipe 28 is connected to the bottom of the tank and a second supply pipe 30 is con-.

y an even permeation of the liquids being forced through the tank, the tank is provided with a false bottom indicated at 32 comprising a series of hard rubber grates 34 mounted on rods '36 running transversely of the tank which act to raise the floor of the tank sulficiently to allow an even flow of the liquid upwardly from all portions of the bottom of the tank.

The cakes wrapped as above described with coarse mesh cloth coverings to permit liquids to penetrate freely through the thread mass are now closely packed. into the tank in tiers in such a manner that the cakes of each successive tier cover the cracks between the cakes of the preceding tier, so that a substantially solid mass of thread is built up to insure an even permeation of the liquid through the cakes placed in the tank.

' The liquids utilized in the several processing operations to which the thread is now subjected to produce the finished product are introduced successively into the tank under sufficient pressure to cause the liquids to penetrate to all parts of the thread mass. During these operations, the coverings on the cakes act to prevent displacement or breakage of the threads under the pressure of the liquids being forced through the thread mass as the impurities are removed. The wrappings tend further to prevent the formation of blow holes where the impurities are thinned out of tracted. This extractor comprises a tub indicated at 42 which is provided with an inner chamber 44 for supporting the cakes perforated to allow the moisture to be forced outwardly by centrifugal force against the walls of the tub 42 where it is drained out through a pipe in the lower portion of the tub. The

perforated inner chamber or cage 44 is rotated at a high velocity to extract the moisture containedjn the cakes which are piled around the outer walls of the chamber.

The cakes are now taken out of the extractor, the outer wrapping removed, and the cakes in this condition placed on trays 46 on a carrier or conveyor 48 which is then moved into the drying chamber 50, as illustrated in Fig. 8. The cakes may be opened out into their cylindrical form either before or after the drying operation. .It is, however, preferred to open out the cakes before they are placed in the drying chamber to eliminate so far as possible any traces of a permanent crease in the threads which might interfere with the operation of winding the thread from the cake. The inserted wrappings 1O enablethe cakes to be opened out readily by hand into their cylindrical shapes without disarranging or breaking the threads and preserve approximately the original shape of the cake.

The threads in the cakes are now in their final form ready for winding onto quills or spools as required for commercial use. A special apparatus has been devised for this purpose and is fully described in a co-pending application, but may be briefly described in connection with Fig. 10 of the drawings as follows: A vertical spindle 50 is rigidly mounted on a bracket 52 on a universal winding machine of ordinary design, generally indicated at 54. A circular disk or platform form 56, the expander disk 58 tending to;

spread the band to its furthest limit to hold the cake yieldingly in its cylindrical shape. The ends of the wrappings 10 are now rolled back, the'upper ends being tucked inside the spring band, and a weighted cover 62 is placed over the top of the spindle to hold the cake and band in the position shown in the drawings. The cover 62 is provided with a flange which extends outwardly somewhat beyond the periphery of the cake so that the thread is led away from the surface of the cake to prevent any possible snarling and breaking of the thread. From this point, the thread i is led upwardly through a pigtail guide located exactly above the spindle and is from' there carried through the usual tensioning and guiding devices to the quill on which the thread is to be'wound.

With this construction and operation of the parts, it will be seen that the inserted wrappings 10 are utilized-to hold the threads in the cake in their relative positions to prevent snarling or breaking of the threads during the handling and processing of the cake up to the time when it is wound from the cake onto the usual quills or spools.

The invention having been described, what is claimed is:

1. The method of producing rayon threads which comprises forming a cake, placing two porous wrappings through the aperture of the cake, flattening the cake in such a manner as to leave a wrapping on eachface of the flattened inner portion of the cake wall, folding the ends of said wrappings over the outside of the cake, subjecting the cake to one or more processing operations and there-. after returning the cake to a substantially cylindrical shape preparatory for winding while retaining said wrapping to support the inner portion of the cake wall.

2. The method of producing rayon threads which comprises forming a cake, placing two porous wrappings through the aperture of the cake, flattening the cake in such a manner as to leave a wrapping on each face of the flattened portion 'of the cake wall, placing an additional wrapping around the exterior of the whole cake, subjecting the cake to one or more processing operations and thereafter removing the outer wrapping and returning the cake to a substantially cylindrical shape preparatory for winding while retaining said inner wrappings to support the inner portion of the cake wall.

3. The method of producing rayon threads which comprises forming cakes, placing insertsthrough the cakes to facilitate in opening out the cakes after processing operations, flattening the cakes, processing the cakes, opening out the cakes, drying the cakes, and thereafter winding the thread from the cakes while maintaining the said inserts in contact with and supporting the inner walls of the cakes.

4. The method of producing rayon threads which comprises forming cakes, placing 1nserts through the cakes to facilitate in opening out the cakes after processing operations, flattening the cakes, processing the cakes, opening out the cakes, placing the cakes on supporting spools for winding while leaving the inserts in contact with the inner walls of the cakes, and thereafter winding the thread from the Cakes.

5. The method of producing rayon threads which comprises forming a cake, placing a porous wrapping through and around the cake, processing the cake, placing the cake on a supporting spool for Winding, removing the wrapping from the outside of the cake while leaving the wrapping in contact with the innervwall of the cake, and thereafter winding the thread from the cake.

6. The method of producing rayon threads which comprises forming a cake, placing a porous wrapping through and around the cake, processing the cake, removing the wrapping from the outside of the cake while supported upon a spool for winding and leaving the wrapping in contact with the inner wall of the cake, and thereafter winding the thread from the cake.

In testimony whereof I have signed my name to this specification.

GEORGE E. LOCKHART. 

